import com.fasterxml.jackson.databind.ObjectMapper;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

@WebServlet("/userInfo")
public class UserInfoServlet extends HttpServlet {
    private ObjectMapper objectMapper = new ObjectMapper();
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String blogId = req.getParameter("blogId");
        if(blogId == null){
            //列表页，获取当前登录用户的信息
            //直接从 session 中获取即可
            getUserInfoFromSession(req,resp);
        }else{
            //详情页，获取文章作者的信息
            //查询数据库
            getUserInfoFromDB(req,resp,Integer.parseInt(blogId));
        }
    }

    private void getUserInfoFromDB(HttpServletRequest req, HttpServletResponse resp, int blogId) throws IOException {
        //1.先根据 blogId 查询 Blog 对象，获取到 userId（作者是谁）
        BlogDao blogDao = new BlogDao();
        Blog blog = blogDao.selectOne(blogId);
        if(blog == null){
            //如果参数传过来的这个 blogId 是随便瞎写的，数据库里没有
            resp.setStatus(404);
            resp.setContentType("text/html;charset=utf8");
            resp.getWriter().write("blogId不存在");
            return;
        }

        //2.根据 userId 查询对应的 User 对象即可
        UserDao userDao = new UserDao();
        User user= userDao.selectById(blog.getUserId());
        if(user == null){
            resp.setStatus(404);
            resp.setContentType("text/html;charset=utf8");
            resp.getWriter().write("blogId 不存在");
            return;
        }

        //3.把 user 对象返回给浏览器了
        user.setPassword("");
        resp.setContentType("application/json;charset=utf8");
        resp.getWriter().write(objectMapper.writeValueAsString(user));
    }

    private void getUserInfoFromSession(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        HttpSession session = req.getSession(false);
        if(session == null){
            resp.setStatus(403);
            resp.setContentType("text/html;charset=utf8");
            resp.getWriter().write("当前未登录");
            return;
        }

        User user =(User) session.getAttribute("user");
        if(user == null){
            resp.setStatus(403);
            resp.setContentType("text/html;charset=utf8");
            resp.getWriter().write("当前未登录");
            return;
        }

        //user 获取到了，把user中的password 干掉，避免信息泄露然后返回
        user.setPassword("");

        resp.setContentType("application/json; charset=utf8");
        resp.getWriter().write(objectMapper.writeValueAsString(user));
    }
}
